Current issues related to oral potassium supplementation are reviewed, with emphasis on recommendations for the appropriate use of potassium supplementation for both replacement and preventive therapy. Dietary potassium intake, potassium-sparing diuretics, and the various forms of oral potassium supplements are reviewed in terms of indications for use, advantages, and limitations. Attention is given to controversial areas, i.e., gastrointestinal tolerance of controlled-release potassium oral dosage preparations and the need for potassium supplementation in hypertensive patients treated with diuretics.